But choices for the right model are limited, and certain choices (e.g., primates) tend to limit the number of animals that can be used. The study has to be big enough to detect a clinically important effect, but not so big it wastes resources.
Without perfect matching of cellular processes and mechanisms of action, there is always the chance that one drug is acting differently on two animal species.
Even basic processes assumed to be similar in mice and men have been found to operate by completely different mechanisms, as reported by Odom et al that liver transcription factors bind differently in mice and men.2 Many side effects can appear in humans that were not picked up by the corresponding animal models, even if administered at a fraction of the dose used in the animal tests.
Perhaps the most egregious instance of this involved TGN1412, an anti-CD28 antibody, which ...
